This invention relates to dental trays for applying a dental compound, such as a fluoride, whitener, etc. to a patient's teeth during a dental procedure, and in particular to a disposable tray which seals against the patient's teeth and/or gums.
Dental trays have long been used to apply compounds, such as fluoride, to patients' teeth. Typically, the trays comprise a pair of arched channels which hold the compound. The trays are sized and shaped to be inserted in a patient's mouth over the patient's teeth. Early trays were rigid, and were commonly made of metal. These trays did not allow for expansion or contraction of the trays to compensate for the different sized arches of patient's mouths. Thus, several trays had to be available so that a proper sized tray could be used on a patient. This could necessitate the use of several trays in a patient's mouth before the appropriate sized tray was found. This would obviously contaminate several trays, only one of which would ultimately be used, and all of which would require cleaning before they could be used again. Thus, not only did the use of rigid trays require extra cleaning, but because they were rigid, they were generally uncomfortable for the patient.
When the trays were made of metal, the trays for the upper and lower teeth were separate from each other. When trays were begun to be made of moldable materials, such as plastics and foams, the trays' upper and lower portions were connected together by a connector or hinge. On some models, the hinge was in the back of the trays. This increased the overall length of the assembly, and for patients with small mouths, made the trays uncomfortable to use. Typically, the hinge element which attaches the upper and lower trays in the back of the trays contacts the back of the patient's jaw at the temporomandibular joint. This is a sensitive spot in a patient's mouth, and the contact of the tray with the jaw at this point often activates the gag reflex, making such trays unsuitable for use, especially on people with smaller mouths.
On other trays, the hinge was formed in the front of the tray assembly, and defined a tab or handle when the tray is inserted in a patient's mouth. Such a handle facilitated insertion of the tray into the patient's mouth and removal of the tray from the patient's mouth. However, the handles for such trays are typically located at the tops of the trays (i.e., the openings of the trays), making them uncomfortable for the patient. Such a tray is shown for example in U.S. Pat. No. 4,173,219 to Lentine. This position of the handle interferes with the patient's lips. In order for the handle to protrude from between the patient's lips, when the mouth is closed, the handle must be bent at two locations, to form an L-shaped element. However, due to the natural resiliency of the material from which the handles are made, the handles will inevitably urge the patient's lips apart. As can be appreciated, this will not be a very natural position for the patient, and the patient may not be comfortable while the tray is in use.
Another problem with the prior trays is that they do not seal well against the patient's teeth or gums. Typically, there are openings through which the compound can escape the tray. This leakage of the compound has long been a problem because the compound which leaks out of the tray is not applied to the teeth and, therefore is wasted. Further, leakage of the compound from the tray into the patient's mouth can cause the patient to gag. Additionally, the compound often does not have a pleasing taste. Various designs have attempted to create a seal. For example, the above noted U.S. Pat. No. 4,173,219 provides for a flange which extends outwardly from the rim of the tray. A similar tray is shown in U.S. Pat. No. 5,211,559 to Hart. However, when the trays shown in these patents are expanded, for example to fit the arch of a larger mouth, the flange on the lingual side of the tray will cause the distance between the lingual and buccal walls of the trays to pull apart. This will make the depth of the tray to become more shallow, and create gaps through which the compound can escape.
Additionally, dental trays are typically packaged in bundles. That is, a plurality (i.e., 20, 50, 100, etc.) are packaged together inside of a single bag or other packaging. This common packaging can lead to cross-contamination. When a dental practitioner (dentist, hygienist, technician, etc.) reaches into the bag to grab one tray, the practitioner will come into contact with other trays as well. Unless the practitioner has a tray ready prior to the dental examination, or unless he removes the gloves he is currently wearing and dons a new pair of gloves to retrieve the dental tray, the other trays in the package will become contaminated.